Cyclic phosphonite stabilizers

ABSTRACT

New phosphonites of the formula ##STR1## wherein R 1  and R 2  independently of one another are a substituted or unsubstituted hydrocarbon radical, or halogen, 
     x and y independently of one another are 0, 1, 2 or 3, 
     n is 2, 3, 4, 5 or 6, and 
     R 3  is a n-valent substituted or unsubstituted aliphatic, alicyclic, aromatic, araliphatic or heterocyclic hydrocarbon residue as stabilizers for organic materials.

The invention relates to new phosphonites, to the manufacture thereof, to their use as stabilisers for plastics and elastomers, and also to the polymers stabilised with these phosphonites.

Phosphonites are known stabilisers, especially 6-phenoxy-dibenz[c,e]-[1,2]-oxaphosphorine and 6-(2,6-di-tert.-butyl-4-methyl-phenoxy)-dibenz[c,e]-[1,2]-oxyphosphorine (Examples 9 and 10 of German Offenlegungsschrift No. 2,034,887). However, these phosphonites do not in every respect meet the high requirements which should be met by a stabiliser, particularly in respect of storage stability, absorption of water, sensitivity to hydrolysis, processing stabilisation, colour improvement, volatility, compatibility and improved stability to light.

It was the object of this invention therefore to provide stabilisers which do not have the disadvantages mentioned or have them to a lesser extent.

Accordingly, the invention relates to phosphonites of the formula I ##STR2## wherein R₁ and R₂ independently of one another are a substituted or unsubstituted hydrocarbon radical, or halogen,

x and y independently of one another are 0, 1, 2 or 3,

n is 2, 3, 4, 5 or 6, and

R₃ is a n-valent substituted or unsubstituted aliphtic, alicyclic, aromatic, araliphatic or heterocyclic hydrocarbon residue.

Phosphonites of the formula I are in particular those wherein

R₁ is C₁ -C₈ alkyl,

x is 0, 1 or 2 and

y is 0,

n is 2, 3, 4, 5 or 6 and

R₃, if n is 2, denotes C₂ -C₂₂ alkylene which may optionally be interrupted by --O--, --S-- or --N(R₄)--, whereby R₄ is C₁ -C₁₈ alkyl, C₅ -C₁₂ cycloalkyl, C₆ -C₁₄ aryl, benzyl or allyl, and R₃ denotes furthermore butenylene or butinylene, C₅ -C₁₂ cycloalkylene, C₆ -C₁₄ arylene, C₇ -C₂₂ alkarylene, 1,4-dithian-2,5-diyl or a residue of the formula --CH₂ --CH₂ --R₅ --, wherein R₅ is a member of the group consisting of ##STR3## wherein R₆ and R₆ ' denote independently of one another hydrogen or C₁ -C₆ alkyl, and R₃ denotes furthermore a group of the formula ##STR4## wherein r is 0 or 1 and R₇ denotes --O--, --S-- or ##STR5## whereby R₈ and R₉ denote independently of one another hydrogen or C₁ -C₈ alkyl or R₈ and R₉ form together with the carbon atom to which they are attached a 5- to 12-membered ring, and R₃ denotes furthermore 1,4-cyclohexylenedimethylene; 1,3,3-trimethyl-cyclohexylene-1,5 or a group of the formula II ##STR6## wherein s denotes 0 or 1, and R₁₀ and R₁₁ denote independently of one another hydrogen, C₁ -C₁₂ alkyl or cyclohexyl, and

R₁₂ denotes --O--, --S-- or ##STR7## whereby R₁₃ denotes hydrogen or C₁ -C₈ alkyl and

R₁₄ denotes hydrogen, C₁ -C₈ alkyl or one of the groups --(CH₂)_(a) --COOR₁₅ or --CH₂ --CH(R₁₆)--S--R₁₇, wherein a is 1 or 2, R₁₅ denotes C₁ -C₁₈ alkyl, C₅ -C₈ cycloalkyl, phenyl or benzyl and R₁₆ is hydrogen or methyl and R₁₇ denotes C₁ -C₁₈ alkyl, cyclohexyl, phenyl, benzyl or a group --(CH₂)_(a) --COOR₁₅ wherein a and R₁₅ are as defined above, or R₁₃ and R₁₄ form together with the carbon atom to which they are attached a 5- to 12-membered ring and R₃ denotes furthermore a group of the formula III ##STR8## wherein t is 0, 1, 2 or 3

R₁₈ is --O-- or --NH--,

b is 1 to 18, and

R₁₀ and R₁₁ are as defined above, and

n is 0 or 1, and

R₃, if n is 3, denotes a trivalent aliphatic C₃ H₅ to C₇ H₁₃ hydrocarbon radical or one of the groups ##STR9## wherein d is 1 to 4 and R₁₉ is a group of the formula IV ##STR10## and R₁₀ and R₁₁ are as defined above, and R₂₀ is a group of the formula IV wherein R₁₀ and R₁₁ are as defined above, or R₂₀ is --CH₂ --CH₂ -- or a group of the formula V ##STR11## R₂₁ denotes a group of the formula VI ##STR12## c is 0, 1, 2 or 3, and R₃, if n is 4, denotes a tetravalent aliphatic C₄ H₆ to C₁₀ H₁₈ hydrocarbon radical or one of the groups VII or VIII ##STR13## wherein R₂₂ is a group of the formula VI and e denotes 1 or 2, and t is as defined above, and

R₃, if n is 5, denotes a pentavalent aliphatic C₅ H₇ to C₁₀ H₁₇ hydrocarbon radical or the group IX ##STR14## R₃, if n is 6, denotes a hexavalent aliphatic C₆ H₈ to C₁₀ H₁₆ hydrocarbon radical.

A substituted or unsubstituted hydrocarbon radical R₁ or R₂ is especially a radical of this type having 1-8 C atoms, such as straight-chain or branched-chain alkyl having 1-8 C atoms, for example methyl, i-propyl or tert.-butyl, and halogen R₁ or R₂ is particularly chlorine.

x is 1 or 2 and most preferably 0, y is preferably 0, and

n is 2, 3, 4, 5 or 6, preferably 2, 3 or 4 and most preferably 2 or 3.

R₃ is a n-valent substituted or unsubstituted aliphatic, alicyclic, aromatic, araliphatic or heterocyclic hydrocarbon residue.

R₃, if n is 2, may be C₂ -C₂₂ alkylene, preferred C₂ -C₉ and most preferred C₂ -C₆ alkylene such as dimethylene, trimethylene, tetramethylene, hexamethylene, octamethylene, nonamethylene, 2,2,4-trimethylhexamethylene, decamethylene, dodecamethylene, octadecamethylene or docosamethylene. The alkylene group may be interrupted by --O--, --S-- or --(N(R₄)-- such as in 2-thiapropylene-1,3; 3-thiapentylene-1,5; 4-oxaheptamethylene, 3,6-dioxaoctylmethylene-1,8 or 3,6-diazaoctylene-1,8. The nitrogen of the aza-group may be substituted by R₄ denoting e.g. C₁ -C₁₈ alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec.-butyl, t.-butyl, n-pentyl, n-hexyl, iso-hexyl, n-octyl, 1,1,3,3-tetramethylbutyl, n-nonyl, decyl, dodecyl, tetradecyl, hexadecyl or octadecyl.

As C₅ -C₁₂ cycloalkyl R₄ is e.g. cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl or cyclododecyl. As C₆ -C₁₀ aryl R₄ is e.g. phenyl or naphthyl.

Examples for R₃ C₅ -C₁₂ cycloalkylene are 1,2-cyclopentylene, 1,3-cyclohexylene, 1,4-cyclohexylene, 1,4-cycloheptylene or 1,2-cyclononylene. C₆ -C₁₀ arylene as R₄ means e.g. 1,4-phenylene or 1,5-naphthylene, preferably 1,4-phenylene.

R₃ may be C₇ -C₂₂ alkarylene, and is preferably a phenylene-1,4-group, which is mono- or di-alkylated particularly in 2-, 2,5- or 2,6-position. In most preferred dialkylated compounds the alkyl-groups in 2- and 5- or 6-position are identical.

Examples of C₇ -C₂₂ alkarylene groups as R₃ are 2,5-di.-t.-butylphenylene-1,4; 2,5-di-t.-pentylphenylene-1,4; 2,5-di-t.-octylphenylene-1,4; 2-t.-butyl-5-methylphenylene-1,4; 2,6-di-t.-butylphenylene, 2,5-diisopropylphenylene-1,4; 2-t.-butylphenylene-1,4; or 2-t.-octylphenylene-1,4.

The groups R₆ and R₆ ' are preferably hydrogen or alkyl groups with 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, n-butyl or n-hexyl.

R₈, R₉, R₁₃ and R₁₄ are in particular C₁ -C₈ -alkyl such as methyl, ethyl, n-propyl, n-butyl, n-hexyl or n-octyl. The preferred meaning of R₈, R₉, R₁₃ and R₁₄ are hydrogen, methyl, ethyl or n-propyl. Most preferably R₈, R₉, R₁₃ and R₁₄ denote hydrogen or methyl.

Furthermore, R₈ and R₉ or R₁₃ and R₁₄ form together with the carbon atom to which they are attached a 5- to 12-membered ring, such as a cyclopentyl-, cyclohexyl-, cycloheptyl-, cyclooctyl- or cyclododecyl-ring.

R₁₀ and R₁₁ are preferably in ortho-position to the free valence and may be C₁ -C₁₂ alkyl, such as methyl, ethyl, isopropyl, sec.-butyl, t.-butyl, t.-pentyl, n-hexyl, 2-ethylhexyl, 1,1,3,3-tetramethylbutyl, n-decyl or 1,1,3,3,5,5-hexamethylhexyl, preferred are C₁ -C₈ alkyl groups.

R₁₅ and R₁₇ may be C₁ -C₁₈ straight chain or branched alkyl, such as methyl, ethyl, n-propyl, n-butyl, n-hexyl, 2-ethyl-hexyl, n-decyl, n-dodecyl, n-tetradecyl or n-octadecyl.

As C₅ -C₈ cycloalkyl R₁₅ may be cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl, preferably cyclohexyl.

R₁₈ denotes --NH-- and particularly --O--,

b may be 1 to 18, preferably 2 to 6.

R₃, if n is 3, may be trivalent aliphatic C₃ H₅ to C₇ H₁₃ hydrocarbon radical, such as ##STR15## R₄, if n is 4, may be a tetravalent aliphatic C₄ H₆ to C₁₀ H₁₈ hydrocarbon radical, such as ##STR16## R₅, if n is 5, may be a pentavalent aliphatic C₅ H₇ to C₁₀ H₁₇ hydrocarbon radical, such as ##STR17## R₆, if n is 5, is a hexavalent aliphatic C₆ H₈ to C₁₀ H₁₆ hydrocarbon radical, such as ##STR18##

Preferred phosphonites of the formula I are those wherein

x and y are 0, and

n is 2, 3 or 4, and

R₃, if n is 2, denotes C₂ -C₉ alkylene which may optionally by interrupted by --O-- or --S--, or R₃ denotes furthermore phenylene, or phenylene which is mono- or di-alkylated with a total number of carbon atoms of 7-22 or a group of the formula II*, ##STR19## wherein denotes 0 or 1, and

R₁₀ and R₁₁ denote independently of one another hydrogen or C₁ -C₈ alkyl and R₁₂ denotes --O--, --S-- or ##STR20## whereby R₁₃ is hydrogen or methyl, and

R₁₄ is hydrogen, methyl or one of the groups --(CH₂)_(a) -- COOR₁₅ or --CH₂ --CH(R₁₆)--S--R₁₇ wherein a and R₁₆ are as defined above and R₁₅ denotes C₁ -C₁₈ alkyl and R₁₇ is C₁ -C₁₂ alkyl or a group of the formula --(CH₂)_(a) --COOR₁₅, wherein a and R₁₅ are as herein defined and R₃ denotes furthermore a group of the formula III wherein R₁₀ denotes methyl or t.butyl, and R₁₁ is t.butyl, R₁₈ is --O-- or --NH--, t is 2, b is 2 to 6 and n is 1, and

R₃, if n is 3, denotes a trivalent aliphatic C₃ H₅ to C₇ H₁₃ hydrocarbon radical or a group of the formula ##STR21## wherein R₂₁ is as defined above, and

R₃, if n is 4, denotes a group of the formula VII, wherein t is 2 and R₁₀ and R₁₁ denote t.butyl.

Most preferred phosphonites of the formula I are those wherein

x and y are 0, and

n is 2 or 3, and

R₃, if n is 2, denotes C₂ -C₆ alkylene, which may be optionally interrupted by --O-- or --S--, or R₃ denotes phenylene or phenylene, which is mono- or di-alkylated with a total number of carbon atoms of 7-22, or a group of the formula II*, wherein s denotes 0 or 1, and R₁₀ and R₁₁ denote independently of one another hydrogen, methyl, t.butyl, t.pentyl or 1,1,3,3-tetramethylbutyl and R₁₂ is --O--, --S-- or ##STR22## wherein R₁₃ and R₁₄ are hydrogen or methyl, and

R₃ denotes furthermore a group of the formula III where-

R₁₀ denotes methyl or t.butyl and R₁₁ denotes t.butyl,

R₁₈ is --O--, t is 2, b is 2 to 6 and n is 1, and

R₃, if n is 3, denotes ##STR23## or a group of the formula ##STR24## R₂₁ is as defined above.

Examples of compounds of the formula I are: ##STR25##

In the formula 1 to 33 above ##STR26##

The phosphonites of the formula I can be produced by methods known per se, especially by esterification or transesterification reactions, for example by reacting about n moles phosphonite of the formula ##STR27## wherein R is a reactive group and R₁, R₂, x and y have the meanings defined in the fore going, with a polyol of the formula

    R.sub.3 --OH).sub.n

wherein R₃ and n have the meanings defined above.

A reactive group R is for example halogen, especially chlorine; alkoxy or substituted or unsubstituted phenoxy.

The reaction can be performed in a manner known per se, for example by heating, preferably to above about 80° C., in particular above 150° C., such as 150°-240° C., for example 220° C., in the course of which H R is split off, wherein R has the meaning defined above; or instead in the presence of bases, such as amines, for example triethylamine, pyridine, N,N-dimethylaniline or sodium carbonate, preferably in an inert solvent, such as aprotic solvents, for example ligroin, toluene, dimethylformamide, dimethylacetamide, sulpholane, methyl ethyl ketone, acetonitrile or ethyl acetate; and also amine bases in excess can be used and these can at the same time serve as solvents (see also German Offenlegungsschrift No. 2,034,887).

The starting materials are known and can, if they are novel, be produced by methods analogous to known methods. P--Cl phosphonites are known, for example, from German Offenlegungsschrift No. 2,034,887, whilst the starting phenols are compounds which have been known for a long time and which are in many cases available commercially.

The compounds of the formula I can be used according to the present invention as stabilisers for plastics and elastomers to protect these from damage caused by the action of oxygen, light and heat. Examples of plastics concerned are the polymers listed in the German Offenlegungsschrift No. 2,456,864 on pages 12-14.

Suitable substrates are, for example:

1. Polymers which are derived from mono-unsaturated hydrocarbons, such as polyolefins, for example low density and high density polyethylene, which can be crosslinked, polypropylene, polyisobutylene, polymethylbut-1-ene and polymethylpent-1-ene.

2. Mixtures of the homopolymers mentioned under 1, for example mixtures of polypropylene and polyethylene, of polypropylene and polybut-1-ene and of polypropylene and polyisobutylene.

3. Copolymers of the monomers on which the homopolymers mentioned under 1 are based, such as ethylene/propylene copolymers, propylene/but-1-ene copolymers, propylene/isobutylene copolymers and ethylene/but-1-ene copolymers, and also terpolymers of ethylene and propylene with a diene, for example hexadiene, di-cyclopentadiene or ethylidenenorbornene.

4. Polystyrene and its copolymers, such as SAN, ABS, IPS, ASA, and EP-modified styrene copolymers.

5. Polyamides.

6. Linear polyesters.

7. Polyurethanes.

8. Polycarbonates.

9. Elastomers, such as polybutadiene, SBR, polyisoprene, polychloroprene and nitrile rubber.

10. Thermoplastic elastomers, such as SBS, SIS and S-EP-S.

11. Polyvinyl chloride and the like.

12. Lubricating oils having a synthetic or mineral base.

The present invention relates also to a process for stabilising polymers against thermooxidative degradation during production, isolation, processing and use, which process comprises incorporating into the polymer at least one compound of the formula I/II.

The compounds of the formula I are incorporated into the substrates at a concentration of 0.005 to 5 percent by weight, calculated relative to the material to be stabilised.

Preferably 0.01 to 1.0 percent by weight, and particularly preferably 0.02 to 0.5 percent by weight, of the compounds, relative to the material to be stabilised, is incorporated into this material. Incorporation is effected for example by mixing at least one of the compounds of the formula I, and optionally further additives, by methods customary in the art, into the polymer either before or during shaping, or alternatively by application of the dissolved or dispersed compounds to the polymers, optionally with subsequent removal of the solvent by evaporation.

The new compounds can also be added in the form of a masterbatch, which contains these compounds for example at a concentration of 2.5 to 25 percent by weight, to the plastics to be stabilised.

In the case of crosslinked polyethylene, the compounds are added before crosslinking.

The invention relates therefore also to the plastics which are stabilised by the addition of 0.01 to 5 percent by weight of a compound of the formula I, and which can optionally contain further additives. The plastics stabilised in this way can be used in the widest variety of forms, for example as films, fibres, tapes and profiles, or as binders for lacquers, adhesives or putties.

Examples of further additives which can be used together with the stabilisers according to the invention are: antioxidants, UV absorbers and light stabilisers, such as 2-(2'-hydroxyhenyl)-benztriazoles, 2,4-bis-(2'-hydroxyphenyl)-6-alkyl-s-triazines, 2-hydroxybenzophenones, 1,3-bis-(2'-hydroxybenzoyl)benzenes, esters of substituted or unsubstituted benzoic acids and acrylates, and also nickel compounds, sterically hindered amines, oxalic acid diamides, metal deactivators, phosphites, compounds which destroy peroxide, polyamide stabilisers, basic Co stabilisers, nucleating agents or other additives, for example plasticisers, lubricants, emulsifiers, fillers, carbon black, asbestos, kaolin, talc, glass fibres, pigments, optical brighteners, flameproofing agents and antistatic agents.

The invention is further illustrated by the following Examples.

EXAMPLES 1-8

22,2 g (0,1 mole) of 2,5-di-t.butyl-hydroquinone and 46,8 g (0,2 moles) of 6-chloro-dibenz[c,e]-[1,2]oxaphosphorine are reacted for 3 hours at a temperature of 200° C. After the reaction has ended, the reaction mixture is held for further two hours at a temperature of 200° C. and cooled afterwards. The resulting ##STR28## melts at 258° C.

The following compounds are obtained analogously: ##STR29## In Examples 2 to 8 Q denotes a residue of the formula ##STR30##

EXAMPLE 9

100 parts of polypropylene powder are mixed together with compound 1 and with pentaerythritol-tetrakis-[3-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionate]. (Antioxidans A) in the amounts given in the following Table.

The resulting mixtures are extruded 5 times successively in a single screw extruder at a maximum of 260° C. with a speed of 100 rpm. The melt index of the polymer is measured after the 1st, 3rd and 5th extrusion, and for this purpose the load is 2160 g, the temperature 230° C. and the melt index is expressed in grams per 10 minutes. The degradation of the polymer is indicated by a rise in the melt index.

    ______________________________________                                                        Melt index after extrusion                                      parts Stabilizer Nr. 1.       3.     5.                                        ______________________________________                                               none           14       42     76                                        0,15  Antioxidans A  4,8      6,5    9,0                                       0,1   1              2,6      4,6    6,8                                       0,05  Antioxidans A                                                            0,05  1              2,5      3,7    5,0                                       0,05  Antioxidans A                                                            0,1   1              2,5      3,5    4,8                                       ______________________________________                                    

EXAMPLE 10

100 parts of unstabilised polyethylene of high density having a molecular weight of about 500,000 ("Lupolen 5260 Z" in powder form from BASF) are in each case mixed dry with 0.05 part of pentaerythritol-tetra-[3-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate] and 0.1 part of the stabilizer of the following Table. The mixtures are kneaded in a Brabender plastograph at 220° C. and at 50 r.p.m. for 20 minutes. During this time, the resistance to kneading is continuously recorded as a torsional moment. Owing to cross-linking of the polymer, there occurs during the kneading period, after an initial constant stage, a rapid increase of the torsional moment. The effectiveness of the stabilizers is reflected in a lengthening of the time of constant torsional moment.

In an additional test the yellowness of the material is measured after 20 minutes kneading in the Brabender plastograph as described above. To assess the degree of yellowing, the Yellowness Index (Y.I.) according to ASTM D-1925/6-3T is measured. An increase of the value of the Y.I. denotes successively more severe discoloration of the material.

    ______________________________________                                                  Time in minutes until                                                                          Y.I. = Discoloration                                           change of torsional                                                                            assessment of the                                     Stabilizer Nr.                                                                          moment          test speciment                                        ______________________________________                                         None     1,5             8,2                                                   1        16              8,8                                                   2        12,5            4,1                                                   3        16              2,4                                                   5        12              2,5                                                   6         4              -1,9                                                  ______________________________________                                     

What we claim is
 1. New phosphonites of the formula I ##STR31## wherein R₁ and R₂ independently of one another are a hydrocarbon radical, or halogen,x and y independently of one another are 0, 1, 2 or 3, n is 2, 3, 4, 5 or 6, and R₃ is a n-valent aliphatic, alicyclic, aromatic, araliphatic each optionally containing N, O, or S atoms or heterocyclic hydrocarbon residue.
 2. Phosphonites according to claim 1 of the formula I whereinR₁ is C₁ -C₈ alkyl, x is 0, 1 or 2 and y is 0, n is 2, 3, 4, 5 or 6 and R₃, if n is 2, denotes C₂ -C₂₂ alkylene which may optionally be interrupted by --O--, --S-- or --N(R₄)--, whereby R₄ is C₁ -C₁₈ alkyl, C₅ -C₁₂ cycloalkyl, C₆ -C₁₄ aryl, benzyl or allyl, and R₃ denotes furthermore butenylene or butynylene, C₅ -C₁₂ cycloalkylene, C₆ -C₁₄ arylene, C₇ -C₂₂ alkarylene, 1,4-dithian-2,5-diyl or a residue of the formula --CH₂ --CH₂ --R₅ --, wherein R₅ is a member of the group consisting of ##STR32## wherein R₆ and R₆ ' denote independently of one another hydrogen or C₁ -C₆ alkyl, and R₃ denotes furthermore a group of the formula ##STR33## wherein r is 0 or 1 and R₇ denotes --O--, --S-- or ##STR34## whereby R₈ and R₉ denote independently of one another hydrogen or C₁ -C₈ alkyl or R₈ and R₉ form together with the carbon atom to which they are attached a ring containing 5 to 12 carbon atoms, and R₃ denotes furthermore 1,4-cyclohexylenedimethylene; 1,3,3-trimethyl-cyclohexylene-1,5 or a group of the formula II ##STR35## wherein s denotes 0 or 1, and R₁₀ and R₁₁ denote independently of one another hydrogen, C₁ -C₁₂ alkyl or cyclohexyl, and R₁₂ denotes --O--, --S-- or ##STR36## whereby R₁₃ denotes hydrogen or C₁ -C₈ alkyl and R₁₄ denotes hydrogen, C₁ -C₈ alkyl or one of the groups --(CH₂)_(a) --COOR₁₅ or --CH₂ --CH(R₁₆)--S--R₁₇, wherein a is 1 or 2, R₁₅ denotes C₁ -C₁₈ alkyl, C₅ -C₈ cycloalkyl, phenyl or benzyl and R₁₆ is hydrogen or methyl and R₁₇ denotes C₁ -C₁₈ alkyl, cyclohexyl, phenyl, benzyl or a group --(CH₂)_(a) --COOR₁₅ wherein a and R₁₅ are as defined above, or R₁₃ and R₁₄ together with the carbon atom to which they are attached form a ring containing 5 to 12 carbon atoms and R₃ denotes furthermore a group of the formula III ##STR37## wherein t is 0, 1, 2 or 3R₁₈ is --O-- or --NH--, b is 1 to 18, and R₁₀ and R₁₁ are as defined above, and n is 0 or 1 with the proviso that t cannot be 0 when n is 0, and R₃, if n is 3, denotes a trivalent aliphatic C₃ H₅ to C₇ H₁₃ hydrocarbon radical or one of the groups ##STR38## wherein d is 1 to 4 and R₁₉ is a group of the formula IV ##STR39## and R₁₀ and R₁₁ are as defined above, and R₂₀ is a group of the formula IV wherein R₁₀ and R₁₁ are as defined above, or R₂₀ is --CH₂ --CH₂ -- or a group of the formula V ##STR40## R₂₁ denotes a group of the formula VI ##STR41## c is 0, 1, 2 or 3, and R₃, if n is 4, denotes a tetravalent aliphatic C₄ H₆ to C₁₀ H₁₈ hydrocarbon radical or one of the groups VII or VIII ##STR42## wherein R₂₂ is a group of the formula VI and e denotes 1 or 2, and t is as defined above, and R₃, if n is 5, denotes a pentavalent aliphatic C₅ H₇ to C₁₀ H₁₇ hydrocarbon radical or the group IX ##STR43## R₃, if n is 6, denotes a hexavalent aliphatic C₆ H₈ to C₁₀ H₁₆ hydrocarbon radical.
 3. Phosphonites according to claim 2 of the formula I whereinx and y are 0, and n is 2, 3 or 4, and R₃, if n is 2, denotes C₂ -C₉ alkylene which may optionally be interrupted by --O-- or --S--, or R₃ denotes furthermore phenylene, or phenylene, which is mono- or dialkylated with a total number of 7 to 22 carbon atoms or a group of the formula II* ##STR44## wherein S denotes 0 or 1, and R₁₀ and R₁₁ denote independently of one another hydrogen or C₁ -C₈ alkyl and R₁₂ denotes --O--, --S-- or ##STR45## whereby R₁₃ is hydrogen or methyl, and R₁₄ is hydrogen, methyl or one of the groups (CH₂)_(a) --COR₁₅ or --CH₂ --CH(R₁₆)--S--R₁₇ wherein a and R₁₆ are as defined above and R₁₅ denotes C₁ -C₁₈ alkyl and R₁₇ is C₁ -C₁₂ alkyl or a group of the formula --(CH₂)_(a) --COOR₁₅, wherein a and R₁₅ are as herein defined and R₃ denotes furthermore a group of the formula III wherein R₁₀ denotes methyl or t.butyl and R₁₁ is t.butyl, R₁₈ is --O-- or --NH--, t is 2, b is 5 to 6 and n is 1, and R₃ if n is 3, denotes a trivalent aliphatic C₃ H₅ to C₇ H₁₃ hydrocarbon radical or a group of the formula ##STR46## wherein R₂₁ is as defined in claim 2, and R₃ if n is 4, denotes a group of the formula VII, wherein t is 2 and R₁₀ and R₁₁ denote t.butyl.
 4. Phosphonites according to claim 3 of the formula I whereinx and y are 0, and n is 2 or 3, and R₃ if n is 2, denotes C₂ -C₆ alkylene, which may be optionally interrupted by --O-- or --S--, or R₃ denotes phenylene, phenylene, which is mono- or di-alkylated with total number of carbon atoms of 7-22, or a group of the formula II* wherein s denotes 0 or 1, and R₁₀ and R₁₁ denote independently of one another hydrogen, methyl, t.butyl, t-pentyl or 1,1,3,3-tetramethylbutyl and R₁₂ is --O--, --S-- or ##STR47## wherein R₁₃ and R₁₄ are hydrogen or methyl, and R₃ denotes furthermore a group of the formula III wherein R₁₀ denotes methyl or t.butyl and R₁₁ denotes t.butyl, R₁₈ is --O--, t is 2, b is 2 to 6 and n is 1, and R₃, if n is 3, denotes ##STR48## or a group of the formula ##STR49## wherein R₂₁ is as defined in claim
 3. 5. Phosphonites according to claim 1, of the formula I, wherein n is 2 or
 3. 6. Phosphonites according to claim 2, wherein n is 2, and R₃ denotes C₇ -C₂₂ alkarylene, or a group of the formula II.
 7. A composition stabilized against oxygen, light and heat comprising an organic material containing from 0.005 to 5% of a phosphonite according to claim
 1. 8. A composition according to claim 7 wherein said organic material is a polyolefin.
 9. The composition according to claim 8 wherein said polyolefin is polypropylene. 